Báo cáo khoa học nông nghiệp: Commercial and High Quality Cultivars of Root and Tuber Crops for Processing Purpose in the Northern and Central Vietnam (MS7)

Ministry of Agriculture & Rural Development Collaboration for Agriculture & Rural Development 008/07VIE Commercial and High Quality Cultivars of Root and Tuber Crops for Processing Purpose in the Northern and Central Vietnam Vietnamese Institution Vietnamese Project Team Leader Australian Institution Australian Project Team Leader Food Crops Research Institute, Ministry of Agriculture and Rural Development Assoc. Prof. Dr. Nguyen Van Tuat Faculty of Agriculture, Food and Natural Resources, University of Sydney Professor Les Copeland Outputs 3 and 4 MS7: Sweet potato processing Preparation of animal feed from sweet potato leaves, vines and roots Extraction of starch from sweet potato May - 2010 I. Introduction Sweet potato1 (Ipomea batatas, a member of the Convolvulacae family), is grown in over 100 countries, mostly by small holder farmers. It has a high yield potential for biomass production, is adapted to a wide range of habitats and soils, and ranks among the world’s top ten food crops on production volume. Sweet potato is a versatile crop. The roots are eaten as vegetables or are processed for diverse uses including making noodles and snack foods, fermentation into alcoholic beverages, and production of starch. The roots are a good source of edible energy in the form of starch, and also provide a source of dietary fibre from non-starch polysaccharides. Sweet potato leaves are rich in vitamins A and C and have relatively high protein content (25–30% of dry matter) compared to other leafy vegetables. The carotene and anthocyanin pigments, which are responsible for the yellow, orange, red, or purple flesh colours of the roots, are a source of natural pigments for the food industry. The roots, leaves and vines are used for livestock feeding, as fresh or dried material, or after fermentation into silage. Fresh sweet potato roots normally contain between 20 and 50% dry matter, depending on cultivar and developmental stage of the plant at harvest. Carbohydrates make up about 90% of dry matter, most of which is starch. The sweetness is due to sugars, mainly maltose but also sucrose, glucose and fructose, which can account for between 5 and 30% of the dry matter. The other major components are non-starch polysaccharides (0.5-7.5%), protein (1-10%) and lipids (1-2%). The composition of the roots varies depending on cultivar, environment for crop growth, cultivation practices, postharvest storage, and influences nutritional, quality and taste/texture properties. Sweet potato roots deteriorate in processing and nutritional quality within about 2-3 weeks after harvest, with loss of moisture and starch content and increase in sugars. Microbial spoilage, particularly in damaged roots, and sprouting are other potential postharvest problems. Processing is an important way of preserving the value of the large amount of biomass produced by sweet potato plants that can not be used by farmers in the short time before postharvest deterioration becomes significant. The overall goals of the project are to improve yield and economic return from sweet potato production in Thanh Hoa, Bac Giang and Quang Tri provinces of Vietnam by - encouraging adoption of improved cultivars and planting materials - providing farmers with greater options for value adding - Enhancing skills of scientists, extension officers and farmers. The specific objectives addressed in this section of the project are to demonstrate simple proof-of-concept methods for i. fermenting sweet potato leaves, vines and roots into a silage-type product for animal feeding, and showing how the process may be adopted by small-holder farmers ii. Large scale extraction of starch from sweet potato roots. 1 Recommended usage to differentiate sweetpotato from the potato (Solanum tuberosa), which belongs to the Solanaceae. 1 Preparation of animal feed from sweet potato leaves, vines and roots In this section of the project, a simple and efficient method was developed for processing sweet potato vines, leaves and roots into livestock feed. The method was demonstrated to local farmers in Bac Giang, Thanh Hoa and Quang Tri provinces. The biological energy of the sweet potato biomass may be conserved, and the consumption time for animal feed prolonged, by microbially fermenting the leaves, vine and roots under anaerobic conditions. Anaerobic conditions have to be maintained subsequently during storage to prevent spoilage of the material due to putrefaction. As described subsequently, salt and a source of energy (cassava starch, rice bran or corn flour) are added to the sweet potato biomass, as a starter for fermentation to provide the right conditions for rapid growth of the appropriate microorganisms. Research scope - Produce livestock feed in Bac Giang, Thanh Hoa and Quang Tri - Demonstrate the benefits to farmers from using the fermented vine-leaves and roots of sweet potatoes. - Solve technical challenges for fermentation processing and usage of the livestock feed. II. Aims The specific aims were to demonstrate technology that could be used to - preserve sweet potato roots from microbial spoilage and vermin and thereby prolong the shelf life of feed for pigs and cattle - improve the digestibility and nutritional quality of the feed by stimulating the production of organic acids such as lactic and acetic acids and amino acids from the biomass - Improve the organizational efficiency of farms by saving energy and labour in preparing feed for livestock and by processing the large volume of sweet potato biomass in a timely manner after harvest and before the next crop. - Increase economic efficiency of livestock growing by utilising all of the sweet potato biomass, including roots unsuitable for human use because they are too small or large, or damaged. III. Methods 3.1. Locations In Bac Giang province: - Bich Son ward in Viet Yen town - Ngoc Chau ward in Tan Yen town - Mai Trung ward in Hiep Hoa town In Thanh Hoa province: - Nguyen Binh ward in Tinh Gia town - Quang Luu in Quang Xuong town 2 - Dong Thanh ward in Dong Son town In Quang Tri province - Vinh Thai ward in Vinh Linh town - Gio Hai ward in Gio Linh town - Hai Quy ward in Hai Lang town 3.2 Ingredients for preparing livestock feed - Sweet potato leaves, vines and roots, sliced and dried under the sun until tender. - Dried rice bran or corn bran or corn flour. - Salt. 3.3 Technology transfer methods - Train and transfer to farmers the techniques to use vine-leaves and roots of sweet potatoes - Design experiments to assess the processing by fermentation of the sweet potato biomass in 15 households in the 3 towns of each province in order to recommend these processes to other households. - Prepare different ingredients for fermentation processes of the sweet potato biomass: o For the sweet potato vine and leaves ③ 90% wilted vine-leaves + 10% rice bran + 0.5% salt ③ 97.5% wilted vine-leaves + 2.5% sugar cane molasses + 0.5% salt ③ 94% fresh vine-leaves + 6% corn flour + 0.5% salt o For the sweet potato roots ③ 10% root + 89.5% fresh vine-leaves + 0.5% salt ③ 25% root + 75% fresh vine-leaves + 0.5% salt ③ 50% root + 50% fresh vine-leaves + 0.5% salt (Note: the starch in the sweet potato roots serves as the energy source and hence sugar, molasses, corn starch, etc., do not have to be added as well) - Instruct the households on the techniques for fermenting sweet potato biomass. The fermentation period to achieve a stable pH was about 2 weeks for sliced-vine-leaves and 3 weeks for sliced-roots. - Show farmers how to preserve the fermented products; if the products are kept in anaerobic conditions created by the air-tight enclosure in plastic, the shelf-life will be extended for up to 6 months without reducing safety and nutrition. - Guide the farmers how to use and mix the fermented feeds with the other materials for pigs with different weight. Pigs of 2.5 months or 18 to 20 kg are able to eat the fermented feed. In the first two days, the pigs should consume 2 meals per day with the mixture of the fermented mash and bran per day. Then they can be fed 3 meals per day (morning, noon and evening). 3.4 Participants - Food Crops Research Institute (FCRI): Nguyen Van Tuat, Truong Cong Tuyen, Nguyen Dat Thoai, Truong Thi Thuy, Nguyen Phan Anh, Tran Quoc Anh, Do Thi Lieu, and Nguyen Thi Hoai 3 - The University of Sydney: Les Copeland, Peter Sharp, Richard Trethowan IV. Research results 4.1. Livestock feed production in Bac Giang province 4.1.1. Fermentation of vine-leaves After about 60 days of growth sweet potato plants are pruned to remove roughly half of the foliage. At this stage the storage roots have not developed but if the vines and leaves are cut properly, the subsequent development of the storage roots will be enhanced. The fermentation process and the ingredients used for vines and leaves were as recommended by the International Potato Centre (Centro Internacional de la Papa-CIP). The quality of the fermented sweet potato product was evaluated by its visual appearance, consistency of texture, the presence of a sweetish, slightly acidic aroma, the absence of foul odours, and its appeal to livestock. After growing 120 days, farmers can harvest sweet potato roots and collect vine-leaves. Roots that are too small or too big roots and damaged roots can be mixed with the vines and leaves for fermentation. It was found that the fermentation process for ingredients of the sliced fresh vine-leaves and sliced roots were convenient, simple and gave a good quality of fermented product. Utilisation of the sweet potato roots could reduce the expenditure for feeding raw materials. Good results were obtained when the experiments were carried out in the nine locations in Bac Giang, Thanh Hoa and Quang Tri provinces. The fermentation products from the different ingredients for sweet potato vine-leaves were evaluated in Bac Giang as shown in the Table 1. Table 1. Evaluation of fermented products of sweet potato vine-leaves in Bac Giang, years 2008-2009 Locations Ingredients Bich Son-Viet Yen (1-5) Ngoc Chau-Tan Yen (1-5) Mai Trung-Hiep Hoa (1-5) CT 1 5 5 5 5 5 4 5 5 4 5 5 3 4 4 5 CT 2 5 4 4 5 4 4 4 5 5 5 4 3 5 4 5 CT 3 5 5 5 5 4 5 5 5 5 5 5 3 4 4 4 Note: Score range 1-5: 1= very bad; 2 = bad, 3 = medium; 4= good; 5 = very good. CT1: 90% wilted vine-leaves + 10% rice bran + 0.5% salt CT2: 97.5% wilted vine-leaves + 2.5% cane molasses + 0.5% salt CT3: 94% fresh vine-leaves + 6% corn flour + 0.5% salt Table 1 showed that the fermented product had either good or very good quality with most scores of 4 and 5. All of the households carried out the experiments properly by following the instructions under the supervision of the FCRI staff. 4 ... - tailieumienphi.vn